Just Smelling Food Can Make You Fat

I recently blogged about synesthesia, where one of your senses affects another. Scientists have now found that one of your senses can affect your entire metabolism.

U.S. and German researchers fed a high-fat diet to three kinds of mice: (1) mice with a normal sense of smell, (2) mice who had lost their sense of smell, and (3) mice with a boosted sense of smell. The mice with normal smell grew to twice their normal weight. The mice with boosted smell gained even more weight. Meanwhile, the mice with reduced smell lost weight.

What’s remarkable is that all three classes of mice received the exact same amount of food.

The study’s conclusion is that there is a connection between the sense of smell and the parts of the brain that regulate metabolism. Without a sense of smell, the mice burned off their food energy instead of retaining it.

“Weight gain isn’t purely a measure of the calories taken in,” says study author Andrew Dillin. “It’s also related to how those calories are perceived.

“If we can validate this in humans, perhaps we can actually make a drug that doesn’t interfere with smell but still blocks that metabolic circuitry. That would be amazing.” (UC Berkeley)

In a separate study, an international team of scientists examined the hypothalamus (the region of the brain that manages metabolism). They found distinct proteomic signatures in mice who were given a high-fat diet. The HFD caused a chronic inflammation of the hypothalamus, resulting in a sustained, perpetual cycle of appetite enhancement.

The researchers believe this work could lead to human therapies to control appetite and weight gain.

The second study used an Agilent Bioanalyzer System and RNA 6000 Nano Kit to evaluate RNA integrity.